This PCB takes a 7-bit binary input ABCDEFG
and decodes the binary into two BCD characters (tens place and ones place). A
is the MSB and G
is the LSB of the binary input.
Pinout
![](https://i0.wp.com/doctor-pasquale.com/wp-content/uploads/2022/12/0-99bcd-pinout.png?resize=199%2C300&ssl=1)
Hardware
This PCB uses a custom-programmed ROM (27C256 OTP) to generate 8-bits of BCD for each binary number. Two 7447 chips are used to decode each segment on a two-digit common-anode display (MAN6410), one for each digit (tens/ones).
Schematic
Click for a larger version.
![](https://i0.wp.com/doctor-pasquale.com/wp-content/uploads/2022/12/0-99bcd-schematic.png?resize=650%2C310&ssl=1)